1. Field of the Invention
The present invention relates to a process for recycling a polyolefin cross-linked substance or a polyolefin foamed substance. In particular, it relates to a process for recycling a multi-layered laminate. The multi-layered laminate includes a layer formed of a polyolefin cross-linked substance or a polyolefin foamed substance, and is utilized as an interior material for making automotive interior component parts, such as an instrument panel, a door trim panel, and so on.
2. Description of the Related Art
Japanese Unexamined Patent Publication (KOKAI) No. 57-8,114, for example, discloses a process for recycling a polyolefin cross-linked substance. In the process, a polyolefin cross-linked substance is independently subjected to an elevated temperature and a high shear force, and is thereby pulverized by heat and shear force. In the process, however, a high shear force is applied to the polyolefin cross-linked substance in an unmelting state. Accordingly, the molecular chains of the polyolefin cross-linked substance are cleaved randomly. As a result, the process suffers from a drawback in that the resulting recycled product is deteriorated considerably in terms of physical properties.
Moreover, Japanese-National-Law Laid-Open Patent Publication No. 7-502,552 discloses a reaction for forcibly cleaving the molecular chains of a cross-linked substance. In the process, a cross-linked substance is brought into contact with an ozone flow in a special halogen solvent to compulsorily cleave the molecular chains. In the process, however, the molecular chains of the cross-linked substance are cleaved randomly. Consequently, the process likewise exhibits a disadvantage in that the physical properties of the resulting recycled product are degraded sharply.